Saliva is an alternate biological matrix for drug testing that has several advantages over more traditional fluids such as blood and urine. Collection is rapid, non-invasive and relatively easy to obtain. Several reports have detailed the appearance of drugs of abuse in saliva but few have compared the excretion profiles of drugs administered by different routes. In this study, subjects were administered three smoked and three intravenous doses of heroin in an ascending dose design. Blood and saliva were collected periodically after drug administration and analyzed by gas chromatography/mass spectrometry (GC/MS) for heroin, 6- acetylmorphine and morphine. In a second study, subjects were administered a single smoked dose of cocaine base, an intranasal dose of cocaine hydrochloride, and an intravenous dose of cocaine hydrochloride on separate occasions. Plasma and saliva were collected and analyzed by GC/MS for cocaine, anhydroecgonine methyl ester (AEME) and seven additional metabolites. Heroin and 6-acetylmorphine were detected in the first saliva sample collected (2 min) following drug administration by both routes. Peak heroin concentrations were achieved quickly, between 2-5 min after intravenous administration and at 2 min after smoked heroin. Peak heroin concentrations in saliva after smoking heroin base ranged from 3534 (2.6 mg) - 20580 (5.2 mg) and after intravenous administration ranged from 6 ng/mL (10 mg heroin HCl) to 30 ng/mL (12 mg). Saliva concentrations of heroin declined rapidly after intravenous administration, reaching the limit of sensitivity of the assay (1 ng/mL) by 60 min. Heroin concentrations in saliva after smoking declined slowly, with detection times ranging from 4-24 h. Cocaine was the major analyte detected in saliva and plasma after smoked and intravenous administration. Peak saliva cocaine concentrations after intravenous administration ranged from 428-1927 ng/mL (N=7) and after smoking from 15852-504880 ng/mL (N=7). Peak plasma cocaine levels after intravenous administration ranged from 122-442 ng/mL (N=7) and after smoking from 46- 291 ng/mL (N=7). The thermal degradation product of cocaine, AEME, was detected in saliva but not blood following smoking. Peak saliva AEME concentrations were achieved at 2 min and ranged from 558-4374 ng/mL (N=7). These are the first reported observations of heroin and metabolites in saliva following heroin smoking and of AEME in saliva after smoking cocaine base. The presence of large quantities of cocaine in saliva after the smoked and intranasal doses was a reflection of oral contamination. Overall, these data indicated the utility of saliva as a test media for detecting recent drug use.